Generation monitoring

Solar generation reporting: what to measure, where to read it, typical deviations and alerts

Metrics and sources

  • Key metrics

    Daily/monthly kWh output, peak power, PR (performance ratio), specific yield kWh/kWp, per-MPPT string currents.

  • Data sources

    Inverter app (Growatt, Deye, Huawei FusionSolar, SolarEdge), meter, net-billing smart meter. The inverter app is the primary source.

  • Comparison baseline

    PVGIS gives expected output for your coordinates and tilt. Output persistently <85% of the model — find the cause.

  • Typical deviations

    Soiling: −5–15%; new shading: −10–40% in shade hours; panel degradation: −0.5%/yr; inverter overheat: midday clipping.

  • Alerts

    Zero output in a sunny hour (fault/disconnect), MPPT string asymmetry >15%, peak down >10% vs last week.

  • Log

    Minimum: monthly output, panel-wash dates, incidents. A year's log reveals the seasonal norm and deviations the app doesn't flag.

Monitoring isn't for pretty charts — it's early degradation detection: output down >10% vs last year's same week in similar weather is a reason to inspect (soiling, shading, inverter).